The present invention provides an emergency control apparatus, and method which maintains the power flow between a battery and an inverter and the operation state of an electric vehicle in the event of failure of a bidirectional DC-DC converter connected between the battery as a power source and the inverter for operating a drive motor.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. An emergency control apparatus for maintaining the operation state of a vehicle in the event of failure of a DC-DC converter, the apparatus comprising: a main switching element electrically connected between an input terminal of an inductor and a battery; a bypass circuit electrically connected between a battery and inverters; an auxiliary switching element provided on the bypass circuit and controlled to selectively open and close the bypass circuit; a failure detection unit that is configured to detect a failure of a DC-DC converter connected between the battery and the inverters wherein the failure detection unit is a current sensor or a voltage sensor provided at input and output terminals of the DC-DC converter; and a controller that is configured to control inverters under zero torque control to minimize output power of drive motors and then turn on the auxiliary switching element to transmit electric power between the battery and the inverters through the bypass circuit when determined determination is made by the controller that there is a failure of the DC-DC converter based on a detection signal from the failure detection unit, wherein the controller determines there is a failure in the DC-DC converter when current is not detected by one or more current sensors, and when an abnormal current or voltage is detected based upon a detection signal from the current sensor or the voltage sensor, respectively, due to disconnection of the inductor or a failed opening of any of a plurality of switching elements or any diodes in the DC-DC converter, wherein the bypass circuit is provided to connect an input terminal of the inductor provided at the rear of the main switching element and positive terminals of DC link terminals of the inverters, so that the bypass circuit is cut off during normal operation of the DC-DC converter and is activated to transmit electric power between the battery and the inverters when a failure of the DC-DC converter is detected to allow the drive motors of a vehicle to operate and enable regenerative braking.
An emergency control system for electric vehicles maintains operation if the DC-DC converter (between the battery and motor inverters) fails. The system has a main switch connecting the battery to an inductor, and a bypass circuit directly connecting the battery to the inverters. An auxiliary switch on the bypass circuit is normally off. A failure detection unit (current or voltage sensor on the DC-DC converter) signals the controller if the DC-DC converter fails due to inductor disconnection, or switch/diode failure (detected as zero or abnormal current/voltage). Upon failure, the controller minimizes motor power using zero torque control, then closes the auxiliary switch, powering the inverters directly from the battery via the bypass. The bypass connects the inductor input to the inverter's DC link positive terminals, enabling motor operation and regenerative braking during the DC-DC converter failure.
2. The apparatus of claim 1 , wherein the auxiliary and main switching elements are relays turned on and off in response to a control signal applied from the controller.
The emergency control system, which maintains electric vehicle operation upon DC-DC converter failure, uses relays as the main and auxiliary switches. These relays, located on the main battery connection and bypass circuit (between battery and motor inverters), are controlled by signals from the system's controller. The failure detection unit signals the controller if the DC-DC converter fails, then the controller minimizes motor power using zero torque control, then closes the auxiliary switch, powering the inverters directly from the battery via the bypass. The bypass connects the inductor input to the inverter's DC link positive terminals, enabling motor operation and regenerative braking during the DC-DC converter failure.
3. An emergency control method for maintaining the operation state of a vehicle in the event of failure of a DC-DC converter, the method comprising: monitoring, at a controller, a failure of the DC-DC converter based on a detection signal of a failure detection unit; controlling inverters under zero torque control to minimize an output power of a motor when it is determined by the controller that there is a failure of the DC-DC converter based on a current value or a voltage value detected by a current sensor or a voltage sensor provided at input and output terminals of the DC-DC converter, wherein the controller determines there is a failure in the DC-DC converter when current is not detected in one or more current sensors, and when an abnormal current or voltage is detected based upon a detection signal from the current sensor or the voltage sensor, respectively, due to disconnection of the inductor or a failed opening of any of a plurality of switching elements or any diodes in the DC-DC converter, and then turning on the switching element to transmit electric power between a battery and inverters through a bypass circuit, wherein the bypass circuit is provided to connect an input terminal of an inductor provided at the rear of a main switching element and positive terminals of DC link terminals of the inverters, so that the bypass circuit is cut off during normal operation of the DC-DC converter and is activated to transmit electric power between the battery and the inverters when a failure of the DC-DC converter is detected to allow drive motors of a vehicle to operate and enable regenerative braking.
An emergency control method maintains electric vehicle operation if the DC-DC converter (between the battery and motor inverters) fails. The controller monitors the DC-DC converter for failure, using current or voltage sensor signals. Failure is detected by zero or abnormal current/voltage, indicating inductor disconnection or switch/diode failure. Upon failure, the controller minimizes motor output using zero torque control. It then closes the auxiliary switch on a bypass circuit, directly connecting the battery to the inverters. The bypass connects an inductor input terminal to the inverter's DC link positive terminals. This enables motor operation and regenerative braking during the DC-DC converter failure when the bypass circuit is activated to transmit electric power between the battery and the inverters.
4. The method of claim 3 , wherein the controller temporarily stops the output of electric power generated during regenerative braking through the inverters when a failure of the DC-DC converter is detected, turns on at least one of the plurality of switching elements, and restarts the output of electric power generated during regenerative braking.
The emergency control method for maintaining electric vehicle operation upon DC-DC converter failure includes temporarily stopping regenerative braking when a DC-DC converter failure is detected (based on current/voltage sensor signals). After the controller detects the failure, minimizes motor output using zero torque control, and closes the auxiliary switch on a bypass circuit connecting the battery to the inverters, the method then reactivates regenerative braking. The bypass connects an inductor input terminal to the inverter's DC link positive terminals. Before reactivating regenerative braking, at least one switching element is turned on. This prevents potential overvoltage situations or instability related to the sudden surge of energy during regenerative braking when the DC-DC converter is not functioning.
5. The method of claim 3 , wherein the auxiliary and main switching elements are a relay turned on and off in response to a control signal applied from the controller.
The emergency control method, which maintains electric vehicle operation upon DC-DC converter failure, uses relays as the main and auxiliary switches. These relays, located on the main battery connection and bypass circuit (between battery and motor inverters), are controlled by signals from the system's controller. The failure detection unit signals the controller if the DC-DC converter fails, then the controller minimizes motor power using zero torque control, then closes the auxiliary switch, powering the inverters directly from the battery via the bypass. The bypass connects the inductor input to the inverter's DC link positive terminals, enabling motor operation and regenerative braking during the DC-DC converter failure.
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May 12, 2010
August 13, 2013
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